NAME
Role::Inspector - introspection for roles
SYNOPSIS
use strict;
use warnings;
use feature qw(say);
{
package Local::Role;
use Role::Tiny; # or Moose::Role, Mouse::Role, etc...
requires qw( foo );
sub bar { ... }
}
use Role::Inspector qw( get_role_info );
my $info = get_role_info('Local::Role');
say $info->{name}; # Local::Role
say $info->{type}; # Role::Tiny
say for @{$info->{api}}; # bar
# foo
DESCRIPTION
This module allows you to retrieve a hashref of information about a given
role. The following role implementations are supported:
* Moose::Role
* Mouse::Role
* Moo::Role
* Role::Tiny
* Role::Basic
* p5-mop-redux
Functions
`get_role_info($package_name)`
Returns a hashref of information about a role; returns `undef` if the
package does not appear to be a role. Attempts to load the package
using Module::Runtime if it's not already loaded.
The hashref may contain the following keys:
* `name` - the package name of the role
* `type` - the role implementation used by the role
* `api` - an arrayref of method names required/provided by the role
* `provides` and `requires` - the same as `api`, but split into
lists of methods provided and required by the role
* `meta` - a metaobject for the role (e.g. a Moose::Meta::Role
object). This key may be absent if the role implementation does
not provide a metaobject
This function may be exported, but is not exported by default.
`does_role($thing, $role)`
Returns a boolean indicating if $thing does role $role. $thing can be
an object, a class name, or a role name.
This should mostly give the same answers as `$thing->DOES($role)`, but
may be slightly more reliable in some cross-implementation (i.e. Moose
roles consuming Moo roles) cases.
This function may be exported, but is not exported by default.
Methods
If you do not wish to export the functions provided by Role::Inspector,
you may call them as a class methods:
my $info = Role::Inspector->get_role_info($package_name);
$thing->blah() if Role::Inspector->does_role($thing, $role);
Extending Role::Inspector
`Role::Inspector::learn { BLOCK }`
In the unlikely situation that you have to deal with some other role
implementation that Role::Inspector doesn't know about, you can teach
it:
use Role::Inspector qw( learn );
learn {
my $r = shift;
return unless My::Implementation::is_role($r);
return {
name => $r,
type => 'My::Implementation',
provides => [ sort(@{My::Implementation::provides($r)}) ],
requires => [ sort(@{My::Implementation::requires($r)}) ],
};
};
An alternative way to do this is:
push @Role::Inspector::SCANNERS, sub {
my $r = shift;
...;
};
You can do the `push` thing without having loaded Role::Inspector.
This makes it suitable for doing inside My::Implementation itself,
without introducing an additional dependency on Role::Inspector.
Note that if you don't provide all of `provides`, `requires`, and
`api`, Role::Inspector will attempt to guess the missing parts.
CAVEATS
* It is difficult to distinguish between Moo::Role and Role::Tiny roles.
(The distinction is not often important anyway.) Thus sometimes the
`type` for a Moo::Role may say "Role::Tiny".
* The way that Role::Basic roles are detected and introspected is a bit
dodgy, relying on undocumented methods.
* Where Moose or Mouse roles define attributes, those attributes tend to
result in accessor methods being generated. However neither of these
frameworks provides a decent way of figuring out which accessor
methods will result from composing the role with the class.
Role::Inspector does its damnedest to figure out the list of likely
methods, but (especially in the case of unusual attribute traits) may
get things wrong from time to time.
BUGS
Please report any bugs to
.
SEE ALSO
Class::Inspector.
AUTHOR
Toby Inkster .
COPYRIGHT AND LICENCE
This software is copyright (c) 2014 by Toby Inkster.
This is free software; you can redistribute it and/or modify it under the
same terms as the Perl 5 programming language system itself.
DISCLAIMER OF WARRANTIES
THIS PACKAGE IS PROVIDED "AS IS" AND WITHOUT ANY EXPRESS OR IMPLIED
WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.